Hi Yoo Jin, this is an iOS issue that Apple acknowledged a good while back but has not yet fixed. This happens in apps other than WayAround. The VoiceOver focus seems to randomly move to a new location, therefore cutting off VoiceOver before it completes speaking all of the text.
The good news is there’s an easy fix! Simply turn VoiceOver off and back on. This should fix the problem. Some users find that this works for a while and then the issue comes back. If that happens, turn VoiceOver off and back on again, and everything should work as expected.